By and large, most condition responsive gauge instruments typically employ a condition responsive element such as a bellows, Bourdon tube, bimetal coil or the like which incurs displacement in response to condition changes to which the element is sensitive. In the usual gauge of quality construction, there is employed an amplifier or "movement" comprised of leverage and gearing operably responsive to displacement motion of the condition responsive element for driving an output shaft supporting a pointer movable relative to a fixed dial plate. The dial registration opposite the pointer position is indicative of the condition state such as pressure or temperature with which the instrument is being operated.
With recent trends toward electronic transmitters for remote readout, it has become known to utilize the condition responsive element for providing the pressure sensitive input thereto. Exemplifying electronic generation of condition values in a photo-optic arrangement are the disclosures of U.S. Pat. Nos. 3,742,233 and 4,109,147. While it is recognized that utilizing a Bourdon tube as the condition responsive element to either drive a mechanical pointer or displace a vane in a photo-optic transmitter is individually known, it has not been known heretofore how to effectively combine the two in a single compact unit without one interfering with operation of the other and in a manner which lends to ready conversion of an existing pressure gauge to a combination gauge-transmitter.